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Handle the case where xShmMap returns SQLITE_BUSY.

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FossilOrigin-Name: 75f5354876c4300a8e53fe551dc837dd383d1e38
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dan
2010-07-15 17:54:14 +00:00
parent c74e4ef4c7
commit 7d4514a4e1
3 changed files with 17 additions and 9 deletions
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12
src/wal.c
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@@ -1866,8 +1866,16 @@ static int walTryBeginRead(Wal *pWal, int *pChanged, int useWal, int cnt){
** WAL_RETRY this routine will be called again and will probably be
** right on the second iteration.
*/
rc = walLockShared(pWal, WAL_RECOVER_LOCK);
if( rc==SQLITE_OK ){
if( pWal->apWiData[0]==0 ){
/* This branch is taken when the xShmMap() method returns SQLITE_BUSY.
** We assume this is a transient condition, so return WAL_RETRY. The
** xShmMap() implementation used by the default unix and win32 VFS
** modules may return SQLITE_BUSY due to a race condition in the
** code that determines whether or not the shared-memory region
** must be zeroed before the requested page is returned.
*/
rc = WAL_RETRY;
}else if( SQLITE_OK==(rc = walLockShared(pWal, WAL_RECOVER_LOCK)) ){
walUnlockShared(pWal, WAL_RECOVER_LOCK);
rc = WAL_RETRY;
}else if( rc==SQLITE_BUSY ){